'His right to cheat beats your right to know.'

British newspapers have hit out at a historic ruling that stops the UK media revealing the identity of a married celebrity dad who allegedly committed adultery - but left the American press free to name him.

"Could anything more starkly expose the law’s failure to keep up with the internet age, in which no judge’s ruling can stop stories from flashing round the world?" it said in an accompanying editorial.

"Celebrities spend fortunes on promoting an image of happy family life to appeal to their fans, who in turn buy their products and enrich them beyond dreams.

"Yet the moment an uncomfortable truth threatens to shake the fans’ trust, they run screaming for an injunction. Whatever happened to the public’s right to know?"

But the decision to grant an injunction sparked fury from legal professionals over the use of children to defend adultery and its implications for freedom of speech.

A New York-based media lawyer, Mark Stephens, branded the move a "knee-jerk reaction" and claimed stars would think they could get away with promiscuity without details being reported in the press by having children.

He told Radio 4's Media Show: "Effectively what we've got now is a watershed moment - an inflection moment.

"So the rich and famous with children are now going to be able to put forward these saccharin images and their primmed and preened images by their spin doctors to the public...

"The message that goes out to celebrities is that if you're going to have a ménage à trois or an open relationship, make sure you've got children because you'll be able to keep it from the public."

Injunctions, and the case against them, came under public scrutiny back in 2011, when Manchester United footballer Ryan Giggs sought desperately to keep details of his affair with ex-Big Brother contestant Imogen Thomas out of the press.

Giggs took out a 'super injunction', meaning it could not even be reported that he had taken out a court order banning publications of the information, but could not combat his name and details of the relationship circulating on social media and in other countries

In May that year, Liberal Democrat MP John Hemming used parliamentary privilege to name Giggs. The footballer gave up all rights to anonymity less than ten months later.